The use of fixtures allows for more behavioural driven tests and simpler
addition of more test cases in future.
However, as ECPubKey is just a wrapper around other strenuously tested
modules, the test data is currently limited to testing a subset of the
total wrapper.
This should probably be done better by using mocked out modules instead.
After a long IRC discussion, it was decided that the use of direct
filepaths instead of the module is a more pure form of testing ,
although it may provide less overall coverage than the mixed integration
style imports used previously.
This will need to be remedied by further integration testing in
/test/integration.
